Scorpionite

Postbags are generally considered canon, unless directly conflicting with lore in-game, in which case the latter has precedence.

Scorpionite is a type of residue which can be found on certain types of ore. While it does not appear in-game, it is mentioned by Nurmof in a Postbag from the Hedge. Nurmof states that it is the reason scorpions are present in mining areas in many different locations and also why they are extremely aggressive. Apparently, scorpionite is considered delicious among scorpions, much like how dragons enjoy eating runite ore.

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Scorpions are addicted to a peculiar residue commonly called scorpionite, which can be found on certain types of ore. Scorpions can't get enough of the stuff, and they seek out all the ore they can find in the hope of getting a bit more scorpionite to eat. It has the bothersome side effect of making them violently territorial, as I'm sure you have noticed.